Nonwoven thermoplastic webs are well known for a wide variety of end-uses, such as for wipes, surgical gowns, dressings, etc. These products are generally made by either meltblowing or spunbonding, both of which are well known in the art. See, for example U.S. Pat. No. 3,978,185 to Bunting et al. dated Aug. 31, 1976, which describes meltblowing and is herein incorporated by reference. Also see U.S. Pat. No. 3,692,618 to Dorschner et al. dated Sept. 19, 1972, which describes spunbonding and is herein incorporated by reference.
Spunbonding entails extruding a multiplicity of continuous thermoplastic polymer strands through a multiplicity of die orifices in a downward direction onto a moving surface where the extruded strands are collected in randomly distributed fashion. The randomly deposited strands are then bonded together in a heated nip to provide sufficient integrity to the resulting nonwoven web of continuous fibers. Spunbonded webs are characterized by a high strength/weight ratio, isotropic strength, high porosity, and good abrasion resistance and are useful for a wide variety of product applications ranging from diaper liners to street repair fabrics.
Meltblowing differs from spunbonding in that the extruded polymer strands are broken up and dispersed into individual fibers by a forced air stream before being deposited onto the collecting surface. In addition, the fibers are substantially cooled by the air so that they do not significantly bond together. Bonding of the web to retain integrity and strength occurs as a separate downstream operation. Meltblown webs are characterized by their softness, bulk, absorbency, low porosity and poor abrasion resistance and are useful for product applications such as surgical drapes and wipes.
Notwithstanding the fact that much nonwoven product development is directed toward products which provide enhanced softness and greater flexibility, there is also a need for an inexpensive nonwoven product which is sufficiently abrasive to serve as a cleaning wipe without using added abrasive materials, yet soft enough to reduce or eliminate scratching the surface being cleaned.